Pile Fabric With Height Difference and Method for Manufacturing the Same

ABSTRACT

A step pile fabric according to the present invention contains a non-shrinkable fiber, and a shrinkable fiber containing a modacrylic copolymer. A composition of the shrinkable fiber containing the modacrylic copolymer contains a polymer composition obtained by mixing i) 60 to 99 parts by weight of a copolymer (A) containing 35 wt % to 98 wt % of acrylonitrile, and 2 wt % to 65 wt % of a total amount of 0.5 wt % to 5.0 wt % of a sulfonic-group-containing monomer and other vinyl monomer, and ii) 1 to 40 parts by weight of a copolymer (B) containing 0 wt % to 90 wt % of acrylonitrile, 2 wt % to 40 wt % of a sulfonic-group-containing monomer, and 0 wt % to 80 wt % of other vinyl monomer containing no halogen. A dry heat shrinkage S of the shrinkable fiber at 130° C. for 5 minutes after dyeing is 15% to 40%. In this way, by performing dyeing using a cationic dye in a low-temperature region so as to suppress shrinkage during dyeing and performing a dry heat treatment after dyeing, a pile fabric with large height difference is provided.

TECHNICAL FIELD

The present invention relates to a step pile fabric produced using modacrylic shrinkable fibers that are dyed using a cationic dye in a specific low-temperature region and, at the same time, controlled to have a desired shrinkage, and a method for manufacturing the same.

BACKGROUND ART

Conventionally, modacrylic fibers have been used widely not only in the field of knitwear but also for boas and high piles because of their hand like animal fur, high softness, vivid color development property, etc. The standing hair portion of natural fur essentially has a two-layer structure consisting of guard hairs and down hairs, and synthetic fibers are used to imitate them, thus producing pile products. As a means for achieving such a structure in the pile products, a generally used method is to provide non-shrinkable fibers and shrinkable fibers that have different shrinkages in a pile portion and allow the shrinkable fibers to shrink at a pile pre-finishing stage so as to achieve a height difference from the difference in the shrinkage at this time. Usually, the shrinkable fibers used at this time are made to shrink at 20% to 40% shrinkage by a dry heat treatment using a pin tenter, thereby achieving the height difference.

When modacrylic shrinkable fibers obtained by the production methods illustrated in patent documents 1 to 3 are dyed at a low temperature equal to or lower than 80° C., they are not dyed sufficiently and achieve only poor color development. On the other hand, when these fibers are dyed in boiling water at 98° C. to 100° C. and used for a pile cloth, they cannot be made to shrink at desired shrinkage by the subsequent dry heat treatment using a tenter.

As described above, in order to achieve the usual dyeing and color development in the modacrylic fibers, it generally has been known that they have to be dyed at a temperature equal to or higher than 90° C. As a method for dyeing modacrylic fibers in a low-temperature region, patent document 4 has suggested a method of dissolving a cationic dye in a dissolved halogenated aliphatic hydrocarbon compound and performing dyeing at a temperature equal to or lower than 80° C. However, because of the dyeing unevenness of the cationic dye, the adverse effect of the halogenated aliphatic hydrocarbon compound on drainage, electrostatic generation in a spinning process, etc., it has been difficult to achieve the usual processability.

Therefore, the pile fabrics using the modacrylic shrinkable fibers that can be dyed in a low-temperature region and achieve a certain shrinkage by the dry heat treatment using a pin tenter have not been reported so far. As a result, there has been no alternative but to rely on spun-dyed shrinkable fibers for the color variation of a down hair portion in pile fabrics.

Moreover, the accuracy of finished height difference is extremely important in imitating natural fur. In general, a method of using fibers designed to have shrinkages suitable for a desired product or a method of using fibers that shrink more than a desired ratio and making a fine adjustment to an excess height difference by cutting a tip of a guard hair portion have been adopted. However, in thus obtained pile fabrics, the fine adjustment to the height difference has been difficult to make. Even after the fine adjustment, too large shrinkage has led to poor hair handling. Further, not only has the process for cutting the tip portion been needed, but also there are considerable manufacturing losses.

Patent document 1: JP 61 (1986)-12910 A

Patent document 2: JP 4 (1992)-119114 A

Patent document 3: JP 2003-268623 A

Patent document 4: JP 49 (1974)-38945 B

DISCLOSURE OF INVENTION Problem to be Solved by the Invention

In the present invention, modacrylic shrinkable fibers can be dyed using a cationic dye in a low-temperature region, and the shrinkage thereof during dyeing is suppressed due to the low-temperature dyeing. Then, a pile fabric containing the thus obtained modacrylic shrinkable fibers is subjected to a dry heat treatment. In this way, the modacrylic shrinkable fibers are made to shrink greatly, thus economically providing a pile fabric having a desired height difference with high quality and a wide range of color variations in a manner simpler than a conventional way.

Means for Solving Problem

A step pile fabric according to the present invention contains a non-shrinkable fiber and a shrinkable fiber containing a modacrylic copolymer. A composition of the shrinkable fiber containing the modacrylic copolymer is a polymer composition obtained by mixing

i) 60 to 99 parts by weight of a copolymer (A) containing 35 wt % to 98 wt % of acrylonitrile, and 2 wt % to 65 wt % of a total amount of 0.5 wt % to 5.0 wt % of a sulfonic-group-containing monomer and other vinyl monomer, and

ii) 1 to 40 parts by weight of a copolymer (B) containing 0 wt % to 90 wt % of acrylonitrile, 2 wt % to 40 wt % of a sulfonic-group-containing monomer, and 0 wt % to 80 wt % of other vinyl monomer containing no halogen. The method includes A dry heat shrinkage S of the shrinkable fiber at 130° C. for 5 minutes after dyeing is 15% to 40%.

A method for manufacturing a step pile fabric according to the present invention is a method for manufacturing a step pile fabric containing a non-shrinkable fiber and a shrinkable fiber containing a modacrylic copolymer. A composition of the shrinkable fiber containing the modacrylic copolymer is a polymer composition obtained by mixing

i) 60 to 99 parts by weight of a copolymer (A) containing 35 wt % to 98 wt % of acrylonitrile, and 2 wt % to 65 wt % of a total amount of 0.5 wt % to 5.0 wt % of a sulfonic-group-containing monomer and other vinyl monomer, and

ii) 1 to 40 parts by weight of a copolymer (B) containing 0 wt % to 90 wt % of acrylonitrile, 2 wt % to 40 wt % of a sulfonic-group-containing monomer, and 0 wt % to 80 wt % of other vinyl monomer containing no halogen. The method includes dyeing the shrinkable fiber containing the modacrylic copolymer at T° C., dyeing the non-shrinkable fiber, manufacturing a pile fabric by using the dyed shrinkable fiber containing the modacrylic copolymer and the dyed non-shrinkable fiber, and subjecting the pile fabric to a heat treatment. A dry heat shrinkage S of the shrinkable fiber at 130° C. for 5 minutes after dyeing at T° C. satisfies Formula (1) below and is 15% to 40%, 70−0.726T≦S(%)≦85−0.726T (where 60≦T≦85)  (1), where dry heat shrinkage S(%)=100×(1−fiber length after shrinkage/fiber length before shrinkage).

The above-noted dyeing temperature T° C. refers to the highest temperature that is reached from the beginning of a dyeing operation (filling a solution in a dyebath) to the end thereof (draining the solution).

Also, the product of the dyeing temperature T° C. and a dyeing time H minutes (T×H) preferably ranges from 1800 to 5100, and the height difference preferably is produced by mixing a non-shrinkable fiber and the modacrylic shrinkable fiber at a weight ratio of 5:95 to 80:20, performing sewing, pre-polishing and pre-shirring, and then performing a dry heat treatment at 110° C. to 150° C.

Also, the non-shrinkable fiber is selected from fibers whose dry heat shrinkage at 130° C. for 5 minutes is smaller than 10% and particularly preferably is a modacrylic fiber. Additionally, it is preferable to achieve a step pile fabric obtained by subjecting a pile cloth containing a modacrylic shrinkable fiber that is made from the above-noted modacrylic copolymers and, after wet spinning, dyed using a cationic dye in a temperature range from 60° C. to 85° C. for achieving a dry heat shrinkage desired as a step pile to a dry heat treatment, etc. with a pin tenter drier at 110° C. to 150° C., thus making it shrink by 15% to 40%.

EFFECTS OF THE INVENTION

A pile cloth containing modacrylic shrinkable fibers that allow dyeing in a region of a temperature lower than a conventional temperature and a shrinkage control is subjected to a dry heat treatment, whereby it becomes readily possible to provide color variations of a down hair portion of a pile fabric having a desired height difference and achieve a high-quality step pile fabric in an economical manner.

DESCRIPTION OF THE INVENTION

The present invention is a method for manufacturing a step pile fabric including dyeing modacrylic shrinkable fibers that are made from a modacrylic copolymer containing 0.5 wt % to 10 wt %, preferably 1.0 wt % to 5.0 wt %, of a sulfonic-group-containing monomer and in which a dyeing temperature (T) and a shrinkage (S) in a dry heat treatment at 130° C. for 5 minutes satisfy the relationship indicated by Formula (1) below by using a cationic dye at a temperature of 60° C. to 85° C., preferably 70° C. to 80° C., and including the modacrylic shrinkable fibers as a down hair component. 70−0.726T≦S(%)≦85−0.726T(60≦T≦85)  (1) Incidentally, the dry heat shrinkage S is given by S(%)=100×(1−fiber length after shrinkage/initial fiber length).

When the sulfonic-group-containing monomer is less than 0.5 wt %, it is not possible to conduct sufficient dyeing in medium color to deep color, which requires a dye exhaustion amount of at least 0.2% omf (“omf” is an abbreviation of “on the mass of fiber”), in dyeing using the cationic dye. Thus, satisfactory hues cannot be obtained. On the other hand, when the sulfonic-group-containing monomer exceeds 10 wt %, fiber agglutination becomes likely to occur in a spinning process.

Examples of the sulfonic-group-containing monomer used in the present invention can include sodium allylsulfonate, sodium methallylsulfonate, sodium vinylsulfonate, sodium styrenesulfonate, sodium 2-acrylamido-2-methylpropanesulfonate and the like, and they can be used alone or in combination of two or more. Among them, sodium methallylsulfonate and sodium 2-acrylamido-2-methylpropanesulfonate are preferable considering cost and polymerizability.

The dyeing temperature lower than 60° C. leads to insufficient dyeing, so that satisfactory color development cannot be achieved. When the dyeing temperature exceeds 85° C., shrinkage occurs during dyeing, and it becomes difficult for a sufficient height difference to be produced in the later processing.

It is appropriate to control the shrinkage during dyeing by the dyeing temperature so that the dry heat shrinkage calculated from Formula (1) is 15% to 40%, preferably 20% to 35%. In this case, the dry heat shrinkage of smaller than 15% after dyeing cannot achieve a significant height difference for a step pile fabric, whereas that exceeding 40% tends to bring about a poor quality of hair handling with a rough root portion in a final product because the fibers in a pile portion shrink while entangling each other at the time of shrinking.

A preferable embodiment is to produce the height difference by mixing a non-shrinkable fiber and this modacrylic shrinkable fiber at a weight ratio of 5:95 to 80:20, preferably 10:90 to 70:30, performing sewing, pre-polishing and pre-shirring, and then performing a dry heat treatment at 110° C. to 150° C., preferably 120° C. to 145° C.

If the ratio of the mixed non-shrinkable fiber is less than 5% or exceeds 95%, the two-layer structure is not clear, resulting in poor natural appearance and feel. Further, when the dry heat treatment is performed at a temperature lower than 110° C., the modacrylic shrinkable fiber shrinks insufficiently, so that a significant step pile fabric cannot be achieved. On the other hand, when the dry heat treatment is performed at a temperature higher than 150° C., the crimps remaining in the fiber forming the pile portion of the pile cloth are set by heat, so that it becomes difficult to remove the crimps in the subsequent polisher process, causing problems of poor quality and productivity of the final product.

Moreover, it is preferable that a composition of the modacrylic copolymer of the modacrylic shrinkable fiber includes a copolymer mixture obtained by mixing 60 to 99 parts by weight of a modacrylic copolymer (A) containing 35 wt % to 98 wt % of acrylonitrile, 0.5 wt % to 5.0 wt % of a sulfonic-group-containing monomer and 2 wt % to 65 wt % of other vinyl monomer and 1 to 40 parts by weight of a modacrylic copolymer (B) containing 0 wt % to 90 wt % of acrylonitrile, 2 wt % to 40 wt % of a sulfonic-group-containing monomer and 0 wt % to 80 wt % of other vinyl monomer containing no halogen. Alternatively, it is preferable that the modacrylic copolymer of the modacrylic shrinkable fiber contains 80 wt % to 98 wt % of acrylonitrile and 2 wt % to 20 wt % of a sulfonic-group-containing monomer and other copolymerizable monomer.

At this time, if the acrylonitrile exceeds 98 wt % in the copolymer (A) of the copolymer mixture, the hand becomes rough, and further the dye-affinity tends to deteriorate. Also, it is not preferable that the other vinyl monomer exceeds 65 wt %, because the hand becomes sticky, so that the lack of voluminousness tends to occur, necessitating special conditions in finish processing such as a polisher process. Further, the sulfonic-group-containing monomer exceeding 5.0 wt % is not preferable because fiber agglutination occurs in the spinning process. Examples of the other vinyl monomer used in the copolymer (A) include vinyl halides and vinylidene halides represented by vinyl chloride, vinylidene chloride, vinyl bromide, vinylidene bromide and the like, acrylic acids, methacrylic acids or alkyl esters thereof, vinyl acetate, acrylamide, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, glycidyl methacrylate, glycidyl acrylate, etc., and they can be used alone or in combination of two or more.

On the other hand, if the acrylonitrile exceeds 90 wt % in the copolymer (B), dyeing in medium color to deep color at 60° C. to 85° C. is difficult. If the other vinyl monomer exceeds 80 wt %, there is a tendency for the fibers to have a lower heat resistance and agglutination in the spinning process. Also, if the sulfonic-group-containing monomer is less than 2 wt %, dyeing in medium color to deep color at 60° C. to 85° C. is difficult. On the other hand, the sulfonic-group-containing monomer exceeding 40 wt % is not preferable because the fiber agglutination and bath elution occur in the spinning process. Examples of the other vinyl monomer containing no halogen used in the copolymer (B) include acrylic acids, methacrylic acids or alkyl esters thereof, vinyl acetate, acrylamide, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, glycidyl methacrylate, glycidyl acrylate, etc. In particular, vinyl acetate and methyl acrylate are preferable in terms of quality and cost.

The ratio of the mixed copolymer (B) to the copolymer (A) is 1 to 40 parts by weight and preferably is 3 to 30 parts by weight. If the copolymer (B) is mixed in a ratio of less than 1 part by weight, the resultant modacrylic shrinkable fiber has insufficient dye-affinity in a low-temperature region. On the other hand, the ratio exceeding 40 parts by weight is not preferable because the fiber agglutination occurs in the spinning process.

The non-shrinkable fiber used in the present invention can be, for example, natural or chemical fibers whose shrinkage at 130° C. for 5 minutes is equal to or smaller than 10% and further preferably is equal to or smaller than 5%. Examples thereof can include natural fibers such as wool and cotton, regenerated fibers such as rayon, polyester fibers such as polyalkylene terephthalate, and modacrylic fibers such as general acrylic and modacrylic fibers. Among them, general acrylic and modacrylic fibers are used in a preferred manner owing to their appropriate finishing temperature conditions close to the shrinkable fiber. The shrinkage of the non-shrinkable fiber larger than 10% is different only slightly from that of the shrinkable fiber, so that a sufficient height difference cannot be produced.

The present invention relates to a method for manufacturing such a step pile. The modacrylic shrinkable fibers obtained by wet spinning from the above-described modacrylic copolymers as raw materials are dyed using the cationic dye at a desired temperature for achieving a desired shrinkage in a temperature range from 60° C. to 85° C. The brand of the cationic dye used for dyeing is not particularly limited but may be a conventionally known brand. For example, “Maxilon (trade name)” series manufactured by Ciba Specialty Chemicals. and “Cathilon (trade name)” series manufactured by Hodogaya Chemical Co., LTD. can be used. Further, although the concentration of the cationic dye is not particularly limited, 0.1 wt % to 3.0 wt % with respect to the weight of the shrinkable fiber is used in the dyeing temperature range in this document in a preferred manner in view of practicability. Although no dyeing accelerator is necessary, a conventionally known dyeing accelerator also may be used according to a known technological example. Additionally, a dyeing machine can be the one of an existing kind.

Subsequently, these modacrylic shrinkable fibers that have been dyed and the non-shrinkable fibers are mixed in a desired ratio to prepare a mixed fiber mass, which then is carded to produce a sliver. Next, a pile fabric is produced (sewed) with a sliver lay-in circular knitting machine. The input density preferably is 500 to 1000 g/m² and particularly preferably is 600 to 900 g/m² in terms of hand, external appearance and weight. Then, after the fibers are placed in a proper orientation by a pre-polishing treatment at 120° C. so that the fibers stand like standing hairs, the pile lengths are aligned by a pre-shirring treatment. Moreover, the fibers are passed through a pin tenter dry heat machine at 110° C. to 150° C. so as to be subjected to a dry heat treatment, so that they are made to shrink by 15% to 40%, which is calculated by Formula (1). At this time, it is more preferable to coat a back surface of the pile with an acrylic ester-based adhesive. Thereafter, the pile is polished at 155° C. and then brushed, followed by a combination of polishing and shirring at 135° C., 120° C. and 90° C. (twice for each process) so as to remove crimps in a surface layer portion of the standing hairs, thereby producing a step pile fabric having a constant pile length.

EXAMPLES

The following is a specific description of the present invention by way of examples. However, the present invention is by no means limited to them. Prior to the description of the examples, analysis and measurement conditions and an evaluation method will be described.

(1) Measurement of Shrinkage of Modacrylic Shrinkable Fiber During Dyeing

The lengths of 20 shrinkable fibers before and after dyeing are measured and averaged respectively, and the shrinkage of the modacrylic shrinkable fibers due to dyeing is calculated by the following formula. Shrinkage (%) of modacrylic shrinkable fiber due to dyeing=100×(1−Da/Db) [wherein Db indicates the length (mm) of the shrinkable fiber before dyeing, and Da indicates the length (mm) of the shrinkable fiber after dyeing.] Incidentally, cut fibers with a small cut length are measured while enlarging the shrinkable fibers with a copying machine or the like. (2) Sensory Evaluation of Achievement Degree of Dyeing

The dyeing and color development evaluations in each concentration were made from visual and sensory points of view on the following criteria.

A: exhausted 70% or more of dye in dyebath

B: exhausted 20% to 70% of dye in dyebath

C: exhausted 20% or less of dye in dyebath

The exhaustion rate is calculated by the following formula by measuring the absorbance at a characteristic absorption wavelength of each dye in the dyebath after dyeing. Formula Exhaustion rate (%)=(1−absorbance in dyebath after dyeing/absorbance in dyebath before dyeing)

In the case of a system where dyes were mixed, measurement was made at the characteristic absorption wavelength of individual dyes, followed by weighted averaging, thus obtaining the exhaustion rate. Incidentally, the absorbance was measured using an ultraviolet and visible spectrophotometer (UV-2550 manufactured by Shimadzu Corporation).

(3) Measurement of Dry Heat Shrinkage in Down Hair Portion (Component) Before and after Dry Heat Treatment Using Pin Tenter

The fibers forming the pile portion in the pile fabric before and after dry heat treatment using pin tenter are made to stand vertically such that the piles were aligned, and then the dry heat shrinkage of the modacrylic shrinkable fibers forming the down hair portion in the step pile fabric was measured using vernier calipers. In other words, the dry heat shrinkage was calculated by the following formula by measuring the length from a root to a tip of a down hair of the fibers forming the down hair portion (component) of the pile portion (not the length from the back surface of the pile fabric) at 10 points and averaging them. Shrinkage (%)=100×(1−Sa/Sb) [wherein Sb indicates the pile length (mm) of the down hair component before the dry heat treatment using the pin tenter, Sa indicates the pile length (mm) of the down hair portion (component) after the dry heat treatment using the pin tenter.] It should be noted that the pile portion in the present invention refers to a standing hair portion other than a portion of a base fabric (a portion of base yarn) of the pile fabric. (4) Sensory Evaluation of External Appearance of Height Difference

With respect to the pile fabrics produced as above, the sensory evaluation of the degree of height difference for the step pile fabric was made from visual and sensory points of view on the following criteria.

A: extremely clear height difference for step pile fabric to be observed.

B: although being a step pile fabric, the border between the two layers not to be observed easily.

C: clear height difference not to be observed, with mixed external appearance

Manufacturing Examples 1 to 4 Reference Examples

A spinning solution prepared by dissolving a modacrylic copolymer containing acrylonitrile (AN)/vinyl acetate (VAc)/sodium styrenesulfonate (3S)=85/13/2 in dimethylformamide (DMF) was extruded through a 0.08 mm spinneret whose number of holes was 15,000 into a 40° C. coagulation bath containing DMF/water=40%/60% and then through five washing and drawing baths sequentially having decreasing solvent concentration, thus performing spinning and drawing by 3.0 times. Subsequently, after being provided with the oil solution, the resultant fibers were dried in an atmosphere at 125° C. Thereafter, a mild treatment was carried out in a pressurized steam atmosphere at 135° C., followed by drawing by 1.8 times in a dry heat atmosphere at 135° C. using heat rollers. Furthermore, mechanical crimps were provided, thereby obtaining fibers having a final fineness of 4.4 decitex (dtex).

The thus obtained fibers were cut to 32 mm and packed in an Obermeyer dyeing machine at a fiber packing density of 0.30 g/cm³, thus performing dyeing. A dyeing formula at this time was 0.26% omf Maxilon Yellow 2RL 200%, 0.09% omf Maxilon Red GRL 200% and 0.17% omf Maxilon Blue GRL 300% (all manufactured by Ciba Specialty Chemicals.), and a target color was light gray. Also, the heating rate at this time was 3° C./min. starting from room temperature, and when 50° C. was reached, the dyes were added, followed by continued heating. When 70° C. (Manufacturing Example 1), 75° C. (Manufacturing Example 2), 80° C. (Manufacturing Example 3) and 100° C. (Manufacturing Example 4) were reached, the fibers were kept at these temperatures for 60 minutes. Further, after dyeing, the dyeing solutions were cooled down, and the dyed fibers were taken out, dewatered centrifugally and then dried at 60° C. in a drier. At this time, the fibers had shrinkages due to dyeing of 1% (Manufacturing Example 1), 8% (Manufacturing Example 2), 17% (Manufacturing Example 3) and 30% (Manufacturing Example 4), respectively.

Manufacturing Examples 5 to 7 Reference Examples

For a spinning solution prepared by dissolving a modacrylic copolymer containing acrylonitrile (AN)/vinyl acetate (VAc)/sodium styrenesulfonate (3S)=85/10/5 in dimethylformamide (DMF), a spinneret similar to that in Manufacturing Example 1 was used under a spinning condition similar to that in Manufacturing Example 1, thus obtaining fibers having a final fineness of 4.4 dtex.

The thus obtained fibers were cut to 32 mm and packed in an Obermeyer dyeing machine at a fiber packing density of 0.30 g/cm³, thus performing dyeing. A dyeing formula at this time was 0.68% omf Maxilon Yellow 2RL 200%, 0.15% omf Maxilon Red GRL 200% and 0.14% omf Maxilon Blue GRL 300% (all manufactured by Ciba Specialty Chemicals.), and a target color was light brown. Also, the heating rate at this time was 3° C./min. starting from room temperature, and when 50° C. was reached, the dyes were added, followed by continued heating. When 70° C. (Manufacturing Example 5), 80° C. (Manufacturing Example 6) and 95° C. (Manufacturing Example 7) were reached, the fibers were kept at these temperatures for 60 minutes. Further, after dyeing, the dyeing solutions were cooled down, and the dyed fibers were taken out, dewatered centrifugally and then dried at 60° C. in a drier. At this time, the fibers had shrinkages due to dyeing of 2% (Manufacturing Example 5), 16% (Manufacturing Example 6) and 27% (Manufacturing Example 7), respectively.

Manufacturing Examples 8 to 9

A modacrylic copolymer (A) containing acrylonitrile (AN)/vinyl chloride (VCL)/sodium styrenesulfonate (3S)=49.5/50/0.5 and a modacrylic copolymer (B) containing acrylonitrile (AN)/methyl acrylate (MA)/sodium 2-acrylamido-2-methylpropanesulfonate (SAM)=30/55/15 were produced. A spinning solution prepared by mixing 8 parts by weight of the latter copolymer (B) with respect to the former copolymer (A) and dissolving them in acetone (Ac) was extruded through a spinneret similar to that in Manufacturing Example 1 into a 20° C. coagulation bath containing Ac/water=30%/70% and then through five washing and drawing baths sequentially having decreasing solvent concentration, thus performing spinning and drawing by 3.0 times. Subsequently, after being provided with the oil solution, the resultant fibers were dried in an atmosphere at 130° C. Thereafter, drawing by 1.8 times was carried out in a dry heat atmosphere at 115° C. using heat rollers. Furthermore, mechanical crimps were provided, thereby obtaining fibers having a final fineness of 4.4 dtex.

The thus obtained fibers were cut to 32 mm and packed in an Obermeyer dyeing machine at a fiber packing density of 0.30 g/cm³, thus performing dyeing. A dyeing formula at this time was the same as that in Manufacturing Example 5, and a target color was light brown. Also, the heating rate at this time was 3° C./min. starting from room temperature, and when 50° C. was reached, the dyes were added, followed by continued heating. When 70° C. (Manufacturing Example 8) and 80° C. (Manufacturing Example 9) were reached, the fibers were kept at these temperatures for 60 minutes. Further, after dyeing, the dyeing solutions were cooled down, and the dyed fibers were taken out, dewatered centrifugally and then dried at 60° C. in a drier. At this time, the fibers had shrinkages due to dyeing of 4% (Manufacturing Example 8) and 18% (Manufacturing Example 9), respectively.

Manufacturing Examples 10 to 13

A modacrylic copolymer (A) containing acrylonitrile (AN)/vinyl chloride (VCL)/sodium styrenesulfonate (3S)=49.5/150/0.5 and a modacrylic copolymer (B) containing acrylonitrile (AN)/methyl acrylate (MA)/sodium 2-acrylamido-2-methylpropanesulfonate (SAM)/sodium methallylsulfonate (MX)=15/54/30/1 were produced. For a spinning solution prepared by mixing 4 parts by weight of the latter copolymer (B) with respect to the former copolymer (A) and dissolving them in acetone (Ac), a spinneret similar to that in Manufacturing Example 7 was used under a spinning condition similar to that in Manufacturing Example 7, thus obtaining fibers having a final fineness of 4.4 dtex.

The thus obtained fibers were cut to 32 mm and packed in an Obermeyer dyeing machine at a fiber packing density of 0.30 g/cm³, thus performing dyeing. A dyeing formula at this time was as follows: for Manufacturing Examples 10, 12 and 13, a target color was light brown, which was the same as that in Manufacturing Example 5, and for Manufacturing Example 11, a target color was light gray, which was the same as that in Manufacturing Example 1. Also, the heating rate at this time was 3° C./min. starting from room temperature, and when 50° C. was reached, the dyes were added, followed by continued heating. When 70° C. (Manufacturing Example 10), 75° C. (Manufacturing Example 11), 80° C. (Manufacturing Example 12) and 85° C. (Manufacturing Example 13) were reached, the fibers were kept at these temperatures for 60 minutes. Further, after dyeing, the dyeing solutions were cooled down, and the dyed fibers were taken out, dewatered centrifugally and then dried at 60° C. in a drier. At this time, the fibers had shrinkages due to dyeing of 4% (Manufacturing Example 10), 8% (Manufacturing Example 11), 17% (Manufacturing Example 12) and 20% (Manufacturing Example 13), respectively.

Manufacturing Examples 14 to 15

A modacrylic copolymer (A) containing acrylonitrile (AN)/vinyl chloride (VCL)/sodium styrenesulfonate (3S)=49.5/50/0.5 and a modacrylic copolymer (B) containing acrylonitrile (AN)/methyl acrylate (MA)/sodium methallylsulfonate (MX)=30/68/2 were produced. For a spinning solution prepared by mixing 30 parts by weight of the latter copolymer (B) with respect to the former copolymer (A) and dissolving them in acetone (Ac), a spinneret similar to that in Manufacturing Example 7 was used under a spinning condition similar to that in Manufacturing Example 7, thus obtaining fibers having a final fineness of 4.4 dtex.

The thus obtained fibers were cut to 32 mm and packed in an Obermeyer dyeing machine at a fiber packing density of 0.30 g/cm³, thus performing dyeing. A dyeing formula at this time was as follows: a target color was light brown, which was the same as that in Manufacturing Example 5. Also, the heating rate at this time was 3° C./min. starting from room temperature, and when 50° C. was reached, the dyes were added, followed by continued heating. When 70° C. (Manufacturing Example 14) and 80° C. (Manufacturing Example 15) were reached, the fibers were kept at these temperatures for 60 minutes. Further, after dyeing, the dyeing solutions were cooled down, and the dyed fibers were taken out, dewatered centrifugally and then dried at 60° C. in a drier. At this time, the fibers had shrinkages due to dyeing of 6% (Manufacturing Example 14) and 20% (Manufacturing Example 15), respectively.

Manufacturing Examples 16 to 17 Comparative Examples

For a spinning solution prepared by dissolving a modacrylic copolymer containing acrylonitrile (AN)/vinyl acetate (VAc)/sodium methallylsulfonate (MS)=85/14.7/0.3 in dimethylacetamide (DMAc), a spinneret similar to that in Example 1 was used under a spinning condition similar to that in Example 1, thus obtaining fibers having a final fineness of 4.4 dtex.

The thus obtained fibers were cut to 32 mm and packed in an Obermeyer dyeing machine at a fiber packing density of 0.30 g/cm³, thus performing dyeing. A dyeing formula at this time was as follows: a target color was light gray, which was the same as that in Manufacturing Example 1. Also, the heating rate at this time was 3° C./min. starting from room temperature, and when 50° C. was reached, the dyes were added, followed by continued heating. When 70° C. (Manufacturing Example 16) and 80° C. (Manufacturing Example 17) were reached, the fibers were kept at these temperatures for 60 minutes. Further, after dyeing, the dyeing solutions were cooled down, and the dyed fibers were taken out, dewatered centrifugally and then dried at 60° C. in a drier. At this time, the fibers had shrinkages due to dyeing of 1% (Manufacturing Example 16) and 16% (Manufacturing Example 17), respectively.

Next, a step pile fabric was produced using the fibers obtained as above.

Example 1 Reference Example

After 70 parts by weight of the modacrylic shrinkable fibers obtained in Manufacturing Example 1 and 30 parts by weight of 51-mm-long 22-dtex commercially-available modacrylic fibers “Kanekaron®” RFM (BR803) (manufactured by KANEKA CORPORATION) were subjected to blending, sewing, pre-polishing and pre-shirring, the temperature of a pin tenter drier for pre-finishing was set to 130° C. so as to produce a mink-like step pile fabric having a final density of 720 g/m² and an average pile length of 22 mm. The down hair portion of this pile fabric had a dry heat shrinkage of 30% as shown in Table 1. The thus produced mink-like pile fabric had clear and natural height difference and favorable hair handling.

Example 2 Reference Example Examples 3 to 5

Using the shrinkable fibers obtained in Manufacturing Examples 5, 8, and 14, mink-like step pile fabrics were produced similarly to Example 1. The thus produced mink-like pile fabrics achieved 28% to 30% dry heat shrinkages of the down hair respectively as shown in Table 1, and had clear and natural height difference and favorable hair handling.

Comparative Examples 1 to 2

Using the shrinkable fibers obtained in Manufacturing Examples 4 and 7, step pile fabrics were produced similarly to Example 1. The shrinkage of the down hair portion was 1% in the case of using the modacrylic shrinkable fibers obtained in Manufacturing Example 4 (Comparative Example 1), and the dry heat shrinkage of the down hair portion was 2% in the case of using the modacrylic shrinkable fibers obtained in Manufacturing Example 7 (Comparative Example 2). Neither of them achieved clear height difference.

Comparative Example 3

Using the shrinkable fibers obtained in Manufacturing Example 16, a mink-like step pile fabric was produced similarly to Example 1. However, in dyeing the modacrylic shrinkable fibers, the hues were insufficient for the target.

Example 6 Reference Example

After 50 parts by weight of the modacrylic shrinkable fibers obtained in Manufacturing Example 2 and 50 parts by weight of 38-mm-long 3.3-dtex commercially-available modacrylic fibers “Kanekaron®” AH (white) (manufactured by KANEKA CORPORATION) were subjected to blending, sewing, pre-polishing and pre-shirring, the temperature of a pin tenter drier for pre-finishing was set to 130° C., and a 2-mm portion from the tip was printed in dark gray, thus producing a chinchilla-like step pile fabric having a final density of 680 g/m² and an average pile length of 18 mm. The down hair portion of this pile fabric had a dry heat shrinkage of 24% as shown in Table 1. The thus produced chinchilla-like pile fabric had clear and natural height difference and favorable hair handling.

Example 7

Using the shrinkable fibers obtained in Manufacturing Example 11, a chinchilla-like step pile fabric was produced similarly to Example 6. The thus produced chinchilla-like pile fabric achieved a 24% dry heat shrinkage of the down hair as shown in Table 1, and had clear and natural height difference and favorable hair handling.

Example 8 Reference Example

After 50 parts by weight of the modacrylic shrinkable fibers obtained in Manufacturing Example 6 and 50 parts by weight of 38-mm-long 3.3-dtex commercially-available modacrylic fibers “Kanekaron®” RCL (brown dyed product) (manufactured by KANEKA CORPORATION) were subjected to blending, sewing, pre-polishing and pre-shirring, the temperature of a pin tenter drier for pre-finishing was set to 130° C. so as to produce a rabbit-like step pile fabric having a final density of 680 g/m² and an average pile length of 18 mm. The down hair portion of this pile fabric had a dry heat shrinkage of 21% as shown in Table 1. The thus produced rabbit-like pile fabric had clear and natural height difference and favorable hair handling.

Examples 9 to 11

Using the shrinkable fibers obtained in Manufacturing Examples 9, 12 and 15, rabbit-like step pile fabrics were produced similarly to Example 8. The thus produced rabbit-like pile fabrics achieved 19% to 21% dry heat shrinkages of the down hair as shown in Table 1, and had clear and natural height difference and favorable hair handling.

Comparative Example 4

Using the shrinkable fibers obtained in Manufacturing Example 17, a rabbit-like step pile fabric was produced similarly to Example 8. However, in dyeing the modacrylic shrinkable fibers, the hues were insufficient for the purpose. TABLE 1 Shrinkage Down Targeted Dyeing during hair Shrinkable pile temp. Degree of hue dyeing shrinkage Height No. fiber used product (° C.) achievement (%) (%) difference Ex. 1 Manuf. Mink-like 70 A 1 30 A (Ref. Ex.) Ex. 1 Ex. 2 Manuf. Mink-like 70 A 2 30 A (Ref. Ex.) Ex. 5 Ex. 3 Manuf. Mink-like 70 A 4 29 A Ex. 8 Ex. 4 Manuf. Mink-like 70 A 4 29 A Ex. 10 Ex. 5 Manuf. Mink-like 70 A 6 28 A Ex. 14 Comp. Manuf. Mink-like 100 A 30 1 C Ex. 1 Ex. 4 Comp. Manuf. Mink-like 95 A 27 2 C Ex. 2 Ex. 7 Comp. Manuf. Mink-like 70 C 1 30 A Ex. 3 Ex. 16 Ex. 6 Manuf. Chinchilla- 75 A 8 24 A (Ref. Ex.) Ex. 2 like Ex. 7 Manuf. Chinchilla- 75 A 8 24 A Ex. 11 like Ex. 8 Manuf. Rabbit- 80 A 16 21 A (Ref. Ex.) Ex. 6 like Ex. 9 Manuf. Rabbit- 80 A 18 20 A Ex. 9 like Ex. 10 Manuf. Rabbit- 80 A 17 21 A Ex. 12 like Ex. 11 Manuf. Rabbit- 80 A 20 19 A Ex. 15 like Comp. Manuf. Rabbit- 80 C 16 21 A Ex. 4 Ex. 17 like 

1-9. (canceled)
 10. A method for manufacturing a step pile fabric comprising a non-shrinkable fiber and a shrinkable fiber comprising a modacrylic copolymer, a composition of the shrinkable fiber comprising the modacrylic copolymer being a polymer composition obtained by mixing i) 60 to 99 parts by weight of a copolymer (A) comprising 35 wt % to 98 wt % of acrylonitrile, and 2 wt % to 65 wt % of a total amount of 0.5 wt % to 5.0 wt % of a sulfonic-group-containing monomer and other vinyl monomer, and ii) 1 to 40 parts by weight of a copolymer (B) comprising 0 wt % to 90 wt % of acrylonitrile, 2 wt % to 40 wt % of a sulfonic-group-containing monomer, and 0 wt % to 80 wt % of other vinyl monomer containing no halogen, the method comprising: dyeing the shrinkable fiber comprising the modacrylic copolymer at T° C.; dyeing the non-shrinkable fiber; manufacturing a pile fabric by using the dyed shrinkable fiber comprising the modacrylic copolymer and the dyed non-shrinkable fiber; and subjecting the pile fabric to a heat treatment; wherein a dry heat shrinkage S of the shrinkable fiber at 130° C. for 5 minutes after the dyeing at T° C. satisfies Formula (1) below and is 15% to 40%, 70−0.726T≦S(%)≦85−0.726T (where 60≦T≦85)  (1), where dry heat shrinkage S (%)=100×(1−fiber length after shrinkage/fiber length before shrinkage).
 11. The method for manufacturing a step pile fabric according to claim 10, wherein the shrinkable fiber is dyed with a cationic dye.
 12. The method for manufacturing a step pile fabric according to claim 10, wherein the product of the dyeing temperature T° C. and a dyeing time H minutes (T×H) ranges from 1800 to
 5100. 13. The method for manufacturing a step pile fabric according to claim 10, wherein the height difference is produced by mixing the non-shrinkable fiber and the shrinkable fiber at a weight ratio of 5:95 to 80:20, performing sewing, pre-polishing and pre-shirring, and then performing a dry heat treatment at 110° C. to 150° C.
 14. The method for manufacturing a step pile fabric according to claim 10, wherein the non-shrinkable fiber is a fiber whose dry heat shrinkage at 130° C. for 5 minutes is smaller than 10%.
 15. The method for manufacturing a step pile fabric according to claim 10, wherein the non-shrinkable fiber is a modacrylic non-shrinkable fiber.
 16. The method for manufacturing a step pile fabric according to claim 10, wherein the dry heat shrinkage S of the shrinkable fiber of the step pile fabric in a dry heat treatment at 110° C. to 150° C. using a pin tenter drier is in a range of 15% to 40%.
 17. The method for manufacturing a step pile fabric according to claim 10, wherein the sulfonic-group-containing monomer in the copolymers (A) and (B) is at least one selected from the group consisting of sodium allylsulfonate, sodium methallylsulfonate, sodium vinylsulfonate, sodium styrenesulfonate and sodium 2-acrylamido-2-methylpropanesulfonate.
 18. The method for manufacturing a step pile fabric according to claim 10, wherein the other vinyl monomer in the copolymer (A) is at least one selected from the group consisting of vinyl halides, vinylidene halides, acrylic acids or alkyl esters thereof, methacrylic acids or alkyl esters thereof, vinyl acetate, acrylamide, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, glycidyl methacrylate and glycidyl acrylate.
 19. The method for manufacturing a step pile fabric according to claim 10, wherein the other vinyl monomer containing no halogen in the copolymer (B) is at least one selected from the group consisting of acrylic acids, methacrylic acids or alkyl esters thereof, vinyl acetate, acrylamide, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, glycidyl methacrylate and glycidyl acrylate.
 20. A step pile fabric comprising a non-shrinkable fiber, and a shrinkable fiber comprising a modacrylic copolymer; wherein a composition of the shrinkable fiber comprising the modacrylic copolymer comprises a polymer composition obtained by mixing i) 60 to 99 parts by weight of a copolymer (A) comprising 35 wt % to 98 wt % of acrylonitrile, and 2 wt % to 65 wt % of a total amount of 0.5 wt % to 5.0 wt % of a sulfonic-group-containing monomer and other vinyl monomer, and ii) 1 to 40 parts by weight of a copolymer (B) comprising 0 wt % to 90 wt % of acrylonitrile, 2 wt % to 40 wt % of a sulfonic-group-containing monomer, and 0 wt % to 80 wt % of other vinyl monomer containing no halogen, and wherein a dry heat shrinkage S of the shrinkable fiber at 130° C. for 5 minutes after dyeing is 15% to 40%.
 21. The step pile fabric according to claim 20, wherein the shrinkable fiber is dyed with a cationic dye.
 22. The step pile fabric according to claim 20, wherein the non-shrinkable fiber is a fiber whose dry heat shrinkage at 130° C. for 5 minutes is smaller than 10%.
 23. The step pile fabric according to claim 20, wherein the non-shrinkable fiber is a modacrylic non-shrinkable fiber.
 24. The step pile fabric according to claim 20, wherein a weight ratio of the non-shrinkable fiber to the shrinkable fiber is 5:95 to 80:20.
 25. The step pile fabric according to claim 20, wherein the dry heat shrinkage S of the shrinkable fiber in a dry heat treatment at 110° C. to 150° C. is in a range of 15% to 40%.
 26. The step pile fabric according to claim 20, wherein the sulfonic-group-containing monomer in the copolymers (A) and (B) is at least one selected from the group consisting of sodium allylsulfonate, sodium methallylsulfonate, sodium vinylsulfonate, sodium styrenesulfonate and sodium 2-acrylamido-2-methylpropanesulfonate.
 27. The step pile fabric according to claim 20, wherein the other vinyl monomer in the copolymer (A) is at least one selected from the group consisting of vinyl halides, vinylidene halides, acrylic acids or alkyl esters thereof, methacrylic acids or alkyl esters thereof, vinyl acetate, acrylamide, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, glycidyl methacrylate and glycidyl acrylate.
 28. The step pile fabric according to claim 20, wherein the other vinyl monomer containing no halogen in the copolymer (B) is at least one selected from the group consisting of acrylic acids, methacrylic acids or alkyl esters thereof, vinyl acetate, acrylamide, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, glycidyl methacrylate and glycidyl acrylate. 